This invention relates generally to film changing equipment for rapidly changing cut films contained in sheaths in X-ray apparatus.
More particularly the invention relates to film changing equipment for rapidly changing films contained in flexible sheaths in radiological X-ray equipment, in which the sheaths containing the films are conveyed by endless conveyor belts which are transparent to X-rays from a magazine into the correct position for the X-ray exposure and then transferred into a delivery box under the control of switch means which cause the conveyor belts either to pick up the next available sheath in the magazine or to leave it in the magazine.
Film changing equipment of the contemplated kind for consecutively exposing cut films contained in sheaths have the advantage over equipment in which unpacked cut film is used, that the film can be loaded, exposed and the sheaths containing the exposed films removed without the necessity of the normal interior lighting being switched off. Even the film changer itself need not be light-proof. Naturally this presupposes that the film sheaths consist of a material that will transmit only the X-rays.
In film changing equipment of this kind (described for instance in German published Patent Specification No. 1,931,919) each sheath containing one film carries entraining elements for engagement by a cooperating entraining element on the film feeding mechanism.
However, in practice the abrupt engagement of the entraining element on the film sheaths by an entraining element on the feed mechanism is found to subject the conveyor belts to such high forces of acceleration that the belts tear and become useless after very short periods of service whenever the film change is effected as quickly as is desirable. This known film changing device is therefore in practice suitable only for slow work requiring no rapid film change.